1. Field of the Invention
The present invention relates to a color tone controller for an endoscope designed to reproduce an observed image on a monitor screen by converting the image of an object of examination into an electric signal by the use of a solid-state image sensor or other similar means.
2. Description of the Related Art
Endoscopes of the type in which an observed image is reproduced on a monitor screen by converting the image of an object of examination into an electric signal have the advantage that it is possible to control the color tone of the reproduced image as desired. However, if the observer cannot grasp the degree (contents) of control of the color tone, he cannot judge the degree to which the balance of colors has been changed by the tone control. Accordingly, it is impossible to judge whether the color of the observed image displayed on the monitor screen represents the actual color of an object of examination or it has been artificially changed by the tone control, that is, the observer cannot make a judgment as to whether the color of the object is normal or not, so that it is impossible to make an accurate diagnosis. In particular, when a recorded image is reproduced later to make an examination, it is completely impossible to make a judgment of color.
Under these circumstances, it is conventional practice to display the degree (contents) of tone control on a monitor screen for each of the three primary colors by means, for example, of color bars which are displayed in these primary colors themselves.
The above-described conventional practice suffers, however, from the following disadvantages. Since the contents of tone control are displayed on the monitor screen by means of relevant colors themselves, it is impossible to grasp specifically and quantitatively the degree to which the color tone has been controlled although it can be judged qualitatively by the sense of vision. Accordingly, the contents of tone control can be estimated only roughly by visual judgment, and it is therefore impossible to make an accurate diagnosis.